[ruby-core:118482] [Ruby master Feature#20613] Implement shadow stack part of (CET) for coroutines

Issue #20613 has been reported by vo.x (Vit Ondruch). ---------------------------------------- Feature #20613: Implement shadow stack part of (CET) for coroutines https://bugs.ruby-lang.org/issues/20613 * Author: vo.x (Vit Ondruch) * Status: Open ---------------------------------------- To fully enable CET, shadow stack needs to be implemented for coroutines. The initial implementation was proposed [here](https://github.com/ruby/ruby/pull/5895) by @ioquatix as part of #18061 -- https://bugs.ruby-lang.org/